Mars, according to Viking 1 Orbiter - Martian Cyclone

This Viking 1 Orbiter image shows a "Low Pressure Cell" near the North Pole of Mars. This Cyclonic Storm is related to Mars' Polar Front, the boundary between the cold polar air and the warmer air to the south.
These clouds are low in the Atmosphere and most likely composed of water ice.

This image was taken in Martian Northern Mid-Summer at 6:55 MLT. The image is approx. 1150 Km across and north is at 11:30.